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PubMed1991

[Juvenile chronic arthritis. A clinical and radiographic study of the chewing apparatus].

The present investigation of a relatively large Danish sample of patients with Juvenile Chronic Arthritis (JCA) revealed high frequencies of symptoms from the masticatory apparatus. 63% of the patients had destructive changes in the region of the mandibular condyles caused by arthritis. In one third of these cases the destructions were severe. Three fourth of the patients with TMJ-affection showed bilateral affection, and one fourth had unilateral affection. TMJ-affection was positively correlated to the duration and the severity of the general disease at the time of examination. Fifty per cent of the patients with TMJ-affection had reduced mouth opening capacity and most of these patients were aware of the problem themselves. The frequency of other symptoms from the TMJ and the jaw musculature was relatively high in the patient group. However, there were no significant differences between these frequencies when the group with TMJ-affection was compared to the group without TMJ-affection except for mouth opening capacity. The patients with TMJ-affection had significantly higher frequencies of frontal and lateral open bite and midline devition when compared to the patients without TMJ-affection. Furthermore, the patients with TMJ-affection had a significantly higher frequency of crowding in the mandibular incisor region than the patients without TMJ-affection. Thus, the study showed that TMJ-affection is common among children with juvenile chronic arthritis, and that the TMJ-affection may result in both functional problems and malocclusion.

Arthritis, Juvenile↗
PubMed1996

A study of the control of disc movement within the temporomandibular joint using the finite element technique.

PURPOSE: A two-dimensional finite element model was developed to simulate and study the in vivo biomechanics and mechanisms of the human temperomandibular joint (TMJ) over the range of normal motion. MATERIALS AND METHODS: A nonlinear model was developed and run using the commercially available ABAQUS software with slide line elements that allowed large displacements and arbitrary contact of surfaces. The three main components of the model were the mandibular condyle, articular disc, and glenoid fossa region of the temporal bone, which were all modeled as deformable bodies. Continuous motion was simulated by doing a static analysis for each of many small steps. A parametric study was performed by determining the maximum stress in each of the three main components as a function of the elasticity of the articular disc. RESULTS: The articular disc was found to move along with condyle in a lifelike manner, even when there were no attachments to the disc. Stress distribution plots showed relatively high stresses deep in the glenoid fossa for most steps. There was a direct, although nonlinear, relationship between maximum stress for all three components and the stiffness of the disc. CONCLUSIONS: This model suggests that muscle contraction is not required to maintain proper disc position. Normal motion results in relatively high stresses deep in the glenoid fossa. The elasticity of the in vivo articular disc may be closer to the lower end of the reported values.

Biomechanical Phenomena↗
PubMed2006

Dynamic compressive properties of the mandibular condylar cartilage.

The mandibular condylar cartilage plays an important role as a stress absorber during function. However, relatively little information is available on its dynamic properties under compression. We hypothesized that these properties are region-specific and depend on loading frequency. To characterize the viscoelastic properties of the condylar cartilage, we performed dynamic indentation tests over a wide range of loading frequencies. Ten porcine mandibular condyles were used; the articular surface was divided into 4 regions, anteromedial, anterolateral, posteromedial, and posterolateral. The dynamic complex, storage, and loss moduli increased with frequency, and these values were the highest in the anteromedial region. Loss tangent decreased with frequency from 0.68 to 0.17, but a regional difference was not found. The present results suggest that the dynamic compressive modulus is region-specific and is dependent on the loading frequency, which might have important implications for the transmission of load in the temporomandibular joint.

Animals↗
PubMed2006

Craniofacial tissue engineering by stem cells.

Craniofacial tissue engineering promises the regeneration or de novo formation of dental, oral, and craniofacial structures lost to congenital anomalies, trauma, and diseases. Virtually all craniofacial structures are derivatives of mesenchymal cells. Mesenchymal stem cells are the offspring of mesenchymal cells following asymmetrical division, and reside in various craniofacial structures in the adult. Cells with characteristics of adult stem cells have been isolated from the dental pulp, the deciduous tooth, and the periodontium. Several craniofacial structures--such as the mandibular condyle, calvarial bone, cranial suture, and subcutaneous adipose tissue--have been engineered from mesenchymal stem cells, growth factor, and/or gene therapy approaches. As a departure from the reliance of current clinical practice on durable materials such as amalgam, composites, and metallic alloys, biological therapies utilize mesenchymal stem cells, delivered or internally recruited, to generate craniofacial structures in temporary scaffolding biomaterials. Craniofacial tissue engineering is likely to be realized in the foreseeable future, and represents an opportunity that dentistry cannot afford to miss.

Absorbable Implants↗
PubMed1979

[Plastic bolting device for the temporomandibular joint for treatment of hypermobility (Re-examination results of the first 28 cases)].

Hypermobility of the mandibular condyle may only slightly be influenced by conservative treatment. On the other hand, all surgical methods, except the one described here include a risk factor concerning nerve or blood vessel damage. The present method limits, by plastic surgery, the joint mobility. 28 such operations were checked for results. The cases with recidivating luxation with trismus and blocking of the mandible reacted very favourably. The cases with habitual subluxation without trismus, and the cases with myofacial pain syndrome were not as favorable, objectively seen. Subjectively, however, the patients feel the operation is a success. Further investigation by control checking on late results is indicated.

Adolescent↗
PubMed1991

Immunohistochemical studies of the extracellular matrix in the condylar cartilage of the human fetal mandible: collagens and noncollagenous proteins.

This study provides data concerning the cells and their extracellular matrix in prenatal human mandibular condylar cartilage. The latter cartilage represents a secondary type of cartilage since it develops late in the morphogenesis of the craniofacial skeleton. The cartilage of the mandibular condyle is actively involved in endochondral ossification, thus showing all the phases of cartilage growth, maturation, and mineralization that precedes de novo bone formation. The present study focused on the localization and distribution of the major macromolecules that are normally encountered in cartilage and bone, including collagens, proteoglycans, fibronectin, osteonectin, osteocalcin, alkaline phosphatase, and anchorin CII. It became clear that the mineralized zone of the cartilage already contained bone-specific antigens; thus the above zone might serve as an essential propagative predecessor in the ossification process.

Alkaline Phosphatase↗
PubMed2001

Unilateral mandibular condylectomy in lambs.

The purpose of this experimental study was to investigate the degree of regeneration of the mandibular condyle after unilateral condylectomy in 10-week-old lambs. The lambs were killed three months after the operation, and the joints examined radiologically and histologically. Scoring systems were used to assess the radiological changes and histological regeneration of the condyle. All joints showed regeneration of the condylar head postoperatively. The maximum degree of regeneration occurred on the medial side rather than the central or lateral areas. There was a significant correlation among the medial, central, and lateral planes (P<0.05). The reformed articular cartilage was irregular and thin (P<0.01), and the disc was thick in the central plane (P<0.01) compared with the control joints. The temporal bone was normal. This study shows that unilateral condylectomy in the growing period results in some condylar regeneration particularly on the medial side and reformation of some irregular and thin articular cartilage.

Animals↗
PubMed1985

Condylar pathology in jaw dysfunction: a semi-quantitative study.

The purpose of the study was to determine whether there was any correlation between temporomandibular joint (TMJ) dysfunction and structure of the mandibular condyle. Condyli from 11 patients with TMJ dysfunction were compared with condyli from 13 patients with clinically uninvolved joints. The following histologic aspects were studied: thickness of the articular soft tissue layer; presence of undifferentiated mesenchyme; progressive and regressive remodelling; and arthrosis, features that are thought to reflect the functional load to the articular surfaces. The only difference between both groups was a higher frequency of regressive remodelling in the condyli from dysfunctioning joints. No significant differences were observed with respect to the other histologic features. It seems that mechanical stress to the joint surfaces does not play a predominant role as a cause of clinical TMJ complaints.

Adolescent↗
PubMed1997

Morphometric and morphological changes in the temporomandibular joint after orthognathic surgery: a magnetic resonance imaging and computed tomography prospective study.

The possible morphological and morphometric changes in the different components of the temporomandibular joint (TMJ) after orthognathic surgery were analysed using computed tomography (CT) transverse scans and sagittal and coronal magnetic resonance imaging (MRI) images. Twenty-four patients with class III dentofacial deformity were studied. Nine had isolated maxillary osteotomies and 15 had combined maxillary and mandibular subcondylar osteotomies (MSO). Ten patients were studied as a control group. The patients were studied clinically, radiographically and with CT and MRI in four different phases in order to locate the position of the mandibular condyle in relation to the glenoid fossa. No statistically significant differences were found in the group of patients who had had isolated maxillary osteotomies throughout the four phases of the study. Patients treated by bimaxillary surgery showed different condylar movements after surgery. Intra-articular effusion was evident during the early postoperative period in patients treated by bimaxillary surgery. Although different changes in the position of the bony components of the TMJ occurred after MSO, these seemed to be transient, with no major alterations in the final outcome in the patients.

Adolescent↗
PubMed1993

Conditioned medium factors of rabbit cranio-facial chondrocytes stimulate their own syntheses of sulfated glycosaminoglycans and DNA.

Previously, we reported methods for isolating chondrocytes from the craniofacial cartilage and culturing them in vitro. The cells actively synthesize glycosaminoglycan (GAG), a marker of the differentiated phenotype of chondrocytes and respond well to PTH and glucocorticoids. It has been suggested that chondrocytes produce somatomedin-like growth factors which support their own growth and GAG synthesis. In the present study, we reported studies on the effect of conditioned medium obtained from cultures of rabbit craniofacial chondrocytes on GAG and DNA syntheses in the same chondrocyte cultures. Serum-free medium, conditioned by exposure to rabbit chondrocytes from mandibular condyle, nasal septum and sphenooccipital synchondrosis in monolayer culture stimulated not only the synthesis of GAG by the same cells but also their own DNA synthesis. The stimulation of the syntheses of GAG and DNA by the conditioned-medium factor were concentration-dependent. In addition, these three kinds of conditioned media stimulated GAG and DNA syntheses of other types of chondrocytes. These findings suggest that rabbit chondrocytes from the craniofacial complex release factors into the culture medium that enhance their own growth and expression of the differentiated phenotype of chondrocytes as well as that of costal chondrocytes.

Animals↗
PubMed2005

Fetal jaw movement affects condylar cartilage development.

Using a mouse exo utero system to examine the effects of fetal jaw movement on the development of condylar cartilage, we assessed the effects of restraint of the animals' mouths from opening, by suture, at embryonic day (E)15.5. We hypothesized that pre-natal jaw movement is an important mechanical factor in endochondral bone formation of the mandibular condyle. Condylar cartilage was reduced in size, and the bone-cartilage margin was ill-defined in the sutured group at E18.5. Volume, total number of cells, and number of 5-bromo-2'-deoxyuridine-positive cells in the mesenchymal zone were lower in the sutured group than in the non-sutured group at E16.5 and E18.5. Hypertrophic chondrocytes were larger, whereas fewer apoptotic chondrocytes and osteoclasts were observed in the hypertrophic zone in the sutured group at E18.5. Analysis of our data revealed that restricted fetal TMJ movement influences the process of endochondral bone formation of condylar cartilage.

Animals↗
PubMed1988

Growth and repair of cartilage: organ culture system utilizing chondroprogenitor cells of condylar cartilage in newborn mice.

The zone of progenitor cells of mandibular condyles of neonatal mice was kept in an organ culture system for up to 8 days. Qualitative and quantitative determinations indicated a pronounced proliferative activity during the initial phases of the culture followed by a differentiation phase and the acquisition of typical hyaline cartilage. The mature hypertrophic chondrocytes were found to be surrounded by cartilage-specific macromolecules such as type II collagen, cartilage proteoglycans, and cartilage anchorin. The extracellular mineralization proceeded along matrix vesicles as is usually noted in vivo. A unique finding in this study was the observation that explants comprising cartilage progenitor cells and their adjacent extracellular matrix succeeded in repairing the damaged condylar in vitro.

Animals↗
PubMed2003

Orthopedically induced condylar growth in a patient with hemifacial microsomia.

OBJECTIVE: Hemifacial microsomia is a congenital abnormality that causes three-dimensional facial asymmetry, affection of the dental occlusion, and failure of growth of the midface in the growing child. This report outlines orthopedically induced condylar growth in a patient with hemifacial microsomia. PATIENT: A 7-year-old girl with hemifacial microsomia, complete absence of the left mandibular condyle, and severe facial asymmetry was treated orthopedically in an early stage by means of a functional appliance. Functional therapy was instituted to stretch the deficient soft tissues to guide and promote skeletal growth and stimulate the affected areas. The treatment was completed with fixed appliances. RESULTS: The effect of the therapy was an excessive change in condylar growth in the affected side. Facial asymmetry was corrected and a symmetric mouth opening was established. CONCLUSIONS: The treatment of patients with hemifacial microsomia should be initiated early enough so that the stimulus could in some degree normalize the deficient tissues and induce bone apposition, and in some cases surgical intervention could be avoided.

Activator Appliances↗
PubMedDate not supplied

Abnormalities in secondary cartilages in four lines of transgenic mice harboring two different types of mutations in the cartilage-specific type II collagen gene.

A histological analysis was performed on two secondary cartilages, the mandibular condyle and the medial end of clavicle, in transgenic mice harboring two different types of mutations in the cartilage-specific type II collagen gene. Considerable differences were observed in the maturation zone of the chondrocytes and the hypertrophic cells of the growth regions of the two secondary cartilages examined between the transgenic mice and their transgene-negative littermates, which served as controls. Looseness of the perichondrium/periosteum was a distinct feature seen in both mutations. However, phenotypic consequences of the mutations in secondary cartilages were less severe than those in primary cartilages. We propose that the differences between primary and secondary cartilages are due to differences in their origin, mode of growth, architecture and behavior under extrinsic factors.

Amino Acid Sequence↗
PubMed1993

The behaviour of mandibular condylar cartilage in cell culture.

This investigation aimed to identify the behaviour of primate mandibular condylar cartilage cells in an in vitro model. Cells were harvested from the mandibular condyles of 1-year-old marmosets and maintained in primary culture for up to 30 d. Cell proliferation, structure, and phenotype were assessed at regular intervals by phase-contrast microscopy, cytologic staining, and immunocytochemistry. Cell growth increased progressively, and cultures reached confluence after 22 d. Cells were initially small and round but later became enlarged and heterogeneous in shape. Polygonal and hypertrophic chondroblast-like cells dominated the mature cultures. Glycosaminoglycan synthesis increased as cultures aged. Type I collagen was produced by early cultures, whereas type II collagen predominated in mature confluent monolayers. It is suggested that this mixed population of cells underwent phenotypic changes in primary cell culture that closely resemble the normal in vivo maturation process.

Animals↗
PubMed1997

[Histological study on the using of autogenous costal perichondrium graft to repair the cartilage of condylar process of mandible].

In order to observe the histological changes of the autogenous perichondrium graft from rib in the repair of injured articular cartilage of the condylar process of mandible, 50 rabbits were used, in which 15 were served as control. The articular cartilage with its subchondral bone were resected and an autogenous graft of costal perichondrium was sutured onto the raw surface of the condylar process, and in the controls, only the articular portion of the condylar process was resected without the application of autogenous costal perichondrium graft. The morphological changes of the newly formed cartilage during the process of its development were investigated by hiostological and autoradiog aphic techniques. The result revealed that 10 days after operation, the graft had increased in thickness and was richly populated form the proliferation of mesenchyme-like cells. Twenty to thirty days later, the chondrocytes were matured and the newly formed cartilage had covered the bony surface of mandibular condyle. At 60 days, the newly formed cartilagenous joint surface became glossy, and the morphology and arrangement of cells tended to be regular simulating the morphology of normal articular cartilage. From the experiment, it could be concluded that (1) The autogenous perichondrium graft placed on the condylar surface of mandible could form new articular cartilage which was similar in tissue morphology to the normal condylar cartilage. (2) The process of development of newly formed cartilage was similar to that of the normal cartilage. (3) The motion and loading on the joint could promote the formation of new cartilage and undergo biological reformation, gradually resulting in normal joint morphology. On this basis, the clinical application of autogenous perichondrium graft to repair injured cartilage of the condylar process of the mandible was feasible.

Animals↗
PubMed1983

Changes in the structure and chemical composition of the mandibular condylar cartilage of the neonatal mouse.

The cartilage of the mandibular condyle of growing mice was used to monitor changes in the content of protein, DNA, hydroxyproline, hydroxylysine, uronic acid, calcium and phosphate. Protein and DNA increased in a stepwise fashion with one spurt seen during the first 2 weeks of post-natal life a second immediately after weaning. Hydroxyproline increased during the entire growth period, i.e. until the 8th post-natal week. Hydroxylysine increased only until week 4. The content of the uronic acid fluctuated and showed highs and lows throughout the growth period. Both calcium and phosphate increased in an almost parallel fashion from birth until the stage of tissue maturation. Morphological studies indicated that the hyaline type of cartilage in the newborn is gradually replaced by a fibrous tissue, which reveals a markedly different structure and composition.

Animals↗
PubMed1998

[The evolution of the lower jaw and the jaw joint, from reptiles to man].

The evolution of the mandible shows two characteristic features: transformation of the angular, articular and square bones in reptiles into the tympanic bone, malleus and incus of the middle ear respectively; and specific volume expansion of the tooth-bearing bone which in mammals comprises the entire mandible. Posture, locomotion and mastication are the basic evolutionary factors which simultaneously provoked 1) a displacement of the temporal regions, 2) a transformation of the face lowering and widening the lower jaw and 3) an elongation of the sutures uniting the different bones in the reptile jaw bone, progressively leading to their separation and transversal orientation. These transformations were accentuated in the biped. Thus in man the temporomandibular joint is in a very lateral and elevated position near the mastoids. The mandibular condyls are elongated transversally with a medial cantilever. The medial part of the meniscus is drawn medially by the lateral pterygoid while the lateral part is drawn laterally by the temporal and masseter fibers. The ramus is oriented vertically and lies close to the cervical spine. The dental arches are displaced posteriorly on the bone and have lost their anterior abutment. The strongest occlusal forces are displaced to the posterior part of the arches and are transmitted vertically to the intra-articular meniscus. All these phenomena are termed extreme adaptations and the temporomandibular joint would (apparently) suffer if the evolution continued. The architectural features of temporomandibular joint overload can be deducted by comparison with the "ideal" architectural conditions for the craniofacial equilibrium.

Adaptation, Physiological↗